From owner-freebsd-questions@FreeBSD.ORG Fri Jul 1 19:27:53 2005 Return-Path: X-Original-To: questions@freebsd.org Delivered-To: freebsd-questions@FreeBSD.ORG Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 077F316A41C; Fri, 1 Jul 2005 19:27:53 +0000 (GMT) (envelope-from mark@gaiahost.coop) Received: from biodiesel.gaiahost.coop (biodiesel.gaiahost.coop [64.95.78.120]) by mx1.FreeBSD.org (Postfix) with ESMTP id B903943D49; Fri, 1 Jul 2005 19:27:52 +0000 (GMT) (envelope-from mark@gaiahost.coop) Received: from pooh.hubcapconsulting.com (host-216-153-147-194.spr.choiceone.net [::ffff:216.153.147.194]) (AUTH: LOGIN mark@hubcapconsulting.com) by biodiesel.gaiahost.coop with esmtp; Fri, 01 Jul 2005 15:27:51 -0400 id 003C4049.42C59937.000038BD Received: by pooh.hubcapconsulting.com (sSMTP sendmail emulation); Fri, 1 Jul 2005 15:27:40 -0400 From: "Mark Bucciarelli" Date: Fri, 1 Jul 2005 15:27:40 -0400 To: freebsd-questions@freebsd.org, "questions@freebsd.org" Message-ID: <20050701192740.GC2593@pooh.hubcapconsulting.com> Mail-Followup-To: freebsd-questions@freebsd.org, "questions@freebsd.org" References: <42C45161.1070402@toldme.com> <20050630204448.8E0F543D4C@mx1.FreeBSD.org> <20050630211028.GP1280@rabbit> <20050630213413.GJ2392@dan.emsphone.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: <20050630213413.GJ2392@dan.emsphone.com> User-Agent: Mutt/1.5.9i Cc: Subject: Re: RAID Cards X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 01 Jul 2005 19:27:53 -0000 On Thu, Jun 30, 2005 at 04:34:13PM -0500, Dan Nelson wrote: > In the last episode (Jun 30), Mark Bucciarelli said: > > > > I don't see the big win in hardware raid. > > The three big plusses for hardware raid are: if you get one with > battery-backed cache (strongly recommended), then the array can cache raid-5 > writes until it gets full stripes, and can hold off doing mirror writes if > there are pending read requests. Ah ... this is certainly a win for an io-bound system. > Also, if your power goes out or the system spontaneously reboots, you won't > have to rebuild parity or resync the mirrors (assuming battery-backed > cache). We pay a lot of money to ensure the lights stay on and sacrifice small animals to avoid spontaneous reboots. > And finally, hardware raid cards will automatically rebuild onto a hot spare I know I could do this with Linux software raid, not sure about gmirror. > if available and you can swap out the dead drive and swap a new spare in > without having to run a single command. Another win. Thanks, your brought up some issues I hadn't thought of. I expect hardware raid cards will go the way of modems and printers and offload their processing to the main CPU. And I guess the choice partly depends on whose software you trust more--free software from FreeBSD or proprietary code written in a cathedral. You can probabaly guess my bias. ;) m